


Past Identities

by RavennaWritesFanfiction



Category: Doom (2005), Star Trek, Star Trek: Alternate Original Series (Movies)
Genre: Crossover, F/M
Language: English
Status: Completed
Published: 2018-12-06
Updated: 2019-02-02
Packaged: 2019-09-12 13:55:16
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 7
Words: 4,908
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16874112
Author URL: https://archiveofourown.org/users/RavennaWritesFanfiction/pseuds/RavennaWritesFanfiction
Summary: Reader and John survive Olduvai, but neither knows the other is still alive. They meet 216 years later at Olduvai under different circumstances.





	1. Death and Reaper: Olduvai

**Author's Note:**

> Started on Tumblr

Lethal. They were absolutely lethal. The R.R.T.S. hadn’t been the same since “Death” joined the squad. She was the token woman on the team and originally they hated having her around. They had nicknamed her Lady, but after a botched mission that ended with her pulling their asses out of the rubble, she was named Death. The pairings had all been established long before she had arrived, but Reaper was incapable of maintaining a partner for more than a mission; they always ended up dead.

It was with a heavy heart that Sarge paired Death and Reaper together. She had so much promise, but she wasn’t likely to return alive. He was beyond wrong. They clicked instantly and didn’t have much of a need for verbal communication. They were always on the same page. He would lead them in and she would do the rest. The Reaper always brought about Death.

Their comradery extended to other parts of their lives; they were content on cleaning their guns while the others acted like idiots. When the new bed arrangements came out, He was horrified that she was to sleep next to Portman. Luckily, Goat was willing to switch with her to avoid a massacre that would absolutely occur if Portman got any ideas.

She had the bed closest to Reaper. It was Death who heard the nightmares when they began again. He had gone years without them and they just started with no warning. It was a gamble on her part, but she went over to him, in his little makeshift cubby, and woke him up. He was so afraid, but she just curled up with him. The next morning, Sarge had a lot to say about her decision; none of which were good. She was reassigned as Destroyers partner and her and John didn’t get a chance to speak.

The next three missions were an absolute nightmare. Although Death and Destroyer were friends, they DID NOT work well together. Neither of them could communicate with each other effectively and it leads to them getting caught by enemy forces. Sarge bailed them out, but it wasn’t an enjoyable trip back to the base. Reaper hadn’t been sleeping due to the horrific nature of the nightmares that haunted every second of sleep. The entire team was suffering in ways that Sarge could never have predicted. John had been just fine before she had joined up, but now he was painfully dependent on her.

Sarge relented after that mission and that night found her in John’s bed, holding him as the nightmares threatened his every dream. Eventually, with the sound of her voice chasing them away to the far edges of his mind, he fell into the first decent night’s sleep he had had in a month. The next mission was golden and once again Reaper led Death in. It was a pairing made in heaven.

Years went by like this. They had started dating, to no one’s surprise. They continued to make a good team. They got matching RRTS tattoos together, they couldn’t know the importance of those tattoos yet. They got a new teammate, The Kid. He was a sweetheart and not cut out for this team. They were all damaged and deranged people, yet The Kid was so… innocent.

They had a new game. Olduvai. John was given the mission off for personal reasons. Death insisted that she would be back before he knew and that she would be fine for this one mission. John couldn’t shake the feeling that he had to go. He barely caught the chopper out, but the look on Death’s face when he did made it worth it.

It was an awkward mission at first. Death was forced to escort Reaper and his sister to the labs. Tense got a new meaning with these two. It was times like this that Death was glad she was an only child.

Shortly after they arrived at the labs, she was recalled to help Sarge and Destroyer clear rooms. All was fine until a call came over the radio that froze John’s blood in his veins.

“We lost Death. She is not responding. Proceed with caution.” Sarge wasn’t the least bit affected. And John had no reason to think she was dead, but the news didn’t sit well. He refused to tell Sam why he was agitated by the news, more so then he would be if it had been one of the other guys.

No one ever did find her, and after Sarge’s rampage, John had to assume the worst and leave Olduvai without her. He left the Marines after that, unable to deal with what he had witnessed and lost. He was Honorably discharged and when he packed his things up, he grabbed her stuff as well. A piece to remember her by. Katherine. He was convinced the others had never learned her real name, but he would never forget it.


	2. Flashbacks and Thanks

Leonard had always made fun of Katherine for her medical training, but here he was, graduating with his medical doctorate. Part of him thought that perhaps he had done this because of her. He was married with a little girl, and he is doing this for a woman who had been gone for the better part of two hundred and twenty years.

When he got divorced, Leonard went back to one of the few things that he knew. Military; or as close to that as still exists. He sat in the bathroom of the shuttlecraft, with his head between his legs. The last time he was in the air was the last time he had seen Katherine. He couldn’t get drunk, but it sure made him feel better to have a bottle to his lips. When the lieutenant came to drag him to an actual seat, he tried to fight it, but it was to no avail. He was seated next to a young man who reeked of a bar and looked like he played the role of punching bag.

_ “Come on Reaper, it will be fun.” Her eyes glimmered with the prospect of mischief and if he was being honest with himself, he would destroy the world to give her the all the mischief she could handle. _

_ “Come on Darlin’, how about we stay in tonight.” There was no way he wanted to stay in, but he couldn’t have her knowing he was a pushover. _

_ “But Reeeeaperrrrr,” he didn’t let her finish the sentence. He stopped her mid-whine with a kiss that said ‘let’s burn this world down’ and was simultaneously maneuvering her out the door while grabbing jackets. _

_ That man picked the wrong girl to get handsy with. Before John could do anything, something had flipped in Kat. The mischief returned, and she was already throwing punches before John could form a thought. _

Jim Kirk. God help this poor kid. Even though his first thought had been of Katherine, Jim was 100% The Kid. Leonard would not let the same thing happen to this one too. Academy, as a med track cadet was nothing like the marines had been, sure there were self-defense classes, but he had to pretend he wasn’t as good as he really was. Even rusty, he could slaughter his competition.

As CMO on the Enterprise, he was able to forget about Katherine, things reminded him less and less of her. He survived Nero, Kahn, and Altamid without becoming Reaper. He was proud of himself. The new Enterprise took off and the last two years of a five-year mission were underway. Jim couldn’t be happier.

That was until a week later they were under attack. It wasn’t a pissed off alien race or a rogue Starfleet Admiral, it was an organization Leonard believed to be long buried on the ash heap of failed organizations: the UAC. The Enterprise wasn’t a random victim, it was a well-planned target. There were wounded everywhere and the medbay had been the first to be destroyed; as if a bomb had been beamed directly there.

With no med supplies, Leonard feared he wouldn’t be able to save the lives of his crewmates. He remembered a time when RRTS5 had been attacked and Katherine had been brought in as med support. His brain went on autopilot as he recalled her actions from that day. He had never been more thankful for her as he was in that moment.

He started grabbing anything that could hold a knot to start tying tourniquets where they were needed. He used debris to prop people up. Anything he could grab became a medical tool. It really made him glad that he had chosen to be a doctor now instead of in the dark ages.


	3. John "Reaper" Grimm

Once the wounded had been taken care of, Leonard returned to the bridge to meet back up with Jim and Spock. Incidentally, it was during the same that the UAC was hailing the now damaged Enterprise.  
“Captain, I am Dr. Matthew Elwood. Ah, Staff Sergeant Grimm, there you are. 216 years looks good on you. Since you are here, it will help me explain the purpose of my attack. You see, John, you thought that you had destroyed the UAC, but here we are.”  
“Excuse me, but who is John Grimm?” Jim was more than slightly confused. Before Elwood could answer, Leonard put his hand on Jim’s shoulder.  
“If you wanted me, you didn’t have to attack the entire crew.” Leonard clenched his jaw. He hadn’t been this mad since before he had become McCoy. He could feel Reaper, scratching at the edges of his mind. It had been a long time, but it was high time Reaper came to visit.  
“I have a little game doctor, though I venture to imagine you will not enjoy it as much as I. I have an assassin who has been ordered to kill you. You have to convince them not to, but you are going to wish you had died at Olduvai.”  
“Who is your assassin and please tell me that you know that I am a super soldier. Your assassin will ultimately fail.”  
“On the contrary, Grimm. They too have been injected with C24. Before you say it, yes, we had C24 stored at other facilities. Yes, we knew Dr. Grimm would inject you with it. No, that hadn’t been the plan, but rather, was a happy accident. I want to see you two battle it out.”  
At that, the screen went black and Leonard sagged. He could feel it growing, the sweat on his palms, the increased heart rate; he thought he was passed all of this, but the past always come back. Jim guided Bones over to the Captain’s chair, although he was confused as to who his best friend really is, he was more concerned at the awful color that filled Bones’ face.  
Once the worst had passed, Leonard began to speak; he couldn’t bring himself to meet Jim’s eyes though.  
“My name is John Grimm. I was a Marine with the RRTS6 team that was sent to the Olduvai Research Facility on Mars, 2048. My sister and I were the only survivors. My fiancée died in that hell hole. She had been my partner and we got separated. If those things didn’t kill her, the explosion did. I was injected with C24 by my sister essentially making me a super soldier who doesn’t age. Like Kahn, for example. My sister died and I went into hiding. Eventually, I rejoined the world as Leonard McCoy. I don’t want to remember my life as John, but if it is a fight he wants, I will rip everyone apart.” Jim deflated at the revelation that their friendship was based on a lie.


	4. Olduvai: Reaper and Death Reunited

Before anyone could do anything, everyone was beamed to a place that could only be described as Olduvai but newer and cleaner. Reaper broke free on pure instinct. A shot was fired, and John heard his whiz past his head.  
“That was a warning shot. I will not miss again. They want you dead and I am the one sent to do it.” He couldn’t see her, and he couldn’t pinpoint her location due to the terrible echo. The more he listened, the clearer her voice became; Katherine. His heart stopped.  
“Do you know who they want you to kill?” The pain laced plea wasn’t lost on Jim or Spock. They knew who it was.  
“I’m not paid to know shit. I am paid to pull this damn trigger.” She sounded angry. She never picked that tone with him.  
“Reaper,” he couldn’t bring himself to finish his sentence. What could he say to deter her from a hit?  
“Bullshit. He’s dead. That entire team is.”  
“Fire a flare and I will look in your direction, tell me I’m lying. I won’t attack, and I am unarmed; you could be long gone by the time we make your position.” She thought about it, what could it hurt?  
Bright green filled the sky and fizzled out, but her location was at the end of the smoke. True to his word, John looked to her. Much to her surprise, the face in her scope was John’s, but she wasn’t convinced.  
“Tattoo.” John held up his left arm and flashed her his Reaper. Her training drained from her mind and her world shattered. She had spent so long moving on, now he was back and she didn’t know whether to be mad or happy.  
She hoped over her barricade wall and moved on them; she didn’t have the sniper, but she was still armed to the teeth. When she reached them, John moved to the front of the crowd and met her. Her first action was to slap him. Hard. Then she pulled him into an inescapable bear hug. He never wanted it to end. He hadn’t even realized that he was crying until she whipped away the tears.  
She pulled on a chain that was around her neck; John had expected his dog tags, but instead, it was the engagement ring. He grabbed her hand, still holding the ring; even after all this time, she still carried it with her everywhere she went. It still sparkled the same as if did the day he picked it out.  
“I remember going to the store with Duke to pick it out. I was so excited that I couldn’t choose. He got so irritated with me. The moment I picked that ring, he told me to quit looking, that was the one. I couldn’t stop imagining it on your finger… I had so many plans for us, Kat.”  
“I know you did, John. I did too. Leave it to the morons at the UAC to fuck it all up for us. I was so in awe by the ring, I almost forgot to say yes.”  
“You answered pretty quickly, I thought.”  
“I really am sorry to interrupt but is there another assassin for in case you fail.” The thought hadn’t occurred to either of them, but as if it were magic, a bullet ripped through Katherine’s shoulder. Getting shot had gotten old, but now with the threat of death eliminated, she was just pissed the fuck off.


	5. About Emotions and A Bullet

**Summary for the Chapter:**

> The happiness of being reunited lasted all of two minutes and gives way to the blame game. Leonard, or rather John, remembers all of the countless times he has thought of her over the years and sets aside his feelings in favor of his medical training. He realizes he has made a possibly fatal mistake in not thinking of the C24 serum's healing properties. Katherine's bullet wound has healed before he could remove the bullet and now all he can do is cling to hope that it doesn't become an issue.

Fleeing is a difficult task when you are trying not to bleed out. There weren't many options for shelter; Katherine knew this. She had personally minimized the chances of escape and failure. Now she was left kicking herself. Only one option remained. A place that Katherine would never go willingly; the sewer. Last time that anyone was down there, to her knowledge, it had been when RRTS had been sent there to quarantine the place and Goat had died. Shaking the memory off, she led the way to the nearest entry. John must have known where they were headed because the whole atmosphere around them shifted.

It hadn't changed much in the last two hundred years. It had been given some extensive repairs, but otherwise, it remained unchanged and the layout was still familiar. Tragedy having sealed it into their minds for eternity. John grew more and more agitated as the venture continued. Jim was the first to call for a break and regroup. Now, sitting still, whatever warm feeling that had transpired between John and Katherine an hour before, had turned cold. Instead of helping the team with their previous knowledge of the research base, they took turns yelling at each other. John accused Katherine of abandoning him while they were on the mission and saving herself; Katherine accused John of not looking for her when they were split up and when the radio acknowledgment of her disappearance was broadcasted through the team. Try as Jim might to side with McCoy, he couldn't. It was obvious that in the heat of the moment, the only person "John" had been thinking about was his sister, Sam. Katherine was right, John hadn't looked for her. He assumed she had been killed like everyone else on the team. As the fighting continued, Jim couldn't figure out how they had ever been able to be in the same room, let alone partners; both professionally and intimately. Where the love was between them was a mystery even for Spock. 

Jim ordered them to stop yelling, afraid it would blow their cover. Leonard or John had gone deathly quiet after that. There were a lot of things of which you could accuse John of, but for all of those, you could never say that he hadn't loved Katherine. One fact, above all others, remained; not a day went by that he hadn't thought of her. For two centuries, he had prayed for an opportunity to see her again, even if it was just a video or image. Now, his prayers were answered and she was sitting right across from him; he should have been holding her close and promising to never let her go, but instead, he was yelling at her. When in his life had things gone so wrong that he would ever do that to her?

He pushed aside all of the feelings that were threatening to drown him in favor of his medical training. He needed to check the wound now that they were relatively safe. He hadn't given the serum, the reason for the reunion, much thought, though now he wishes he had. The wound was healed and their current environment did not lend itself to cutting the bullet out of her shoulder. He had no way of removing it, so all he could do was hope that the bullet wouldn't become a further issue and that they may escape Olduvai without further incident.

Why should he get to be so lucky? Apparently, fate was thinking the same thing. The group picked up and continued to trudge through the sewer. Not even a half hour later, Katherine's lower back and legs went numb. It was cause for Leonard to worry, but it served only as a mild irritant for Katherine. They kept walking, although Leonard was practically stepping on her he was so close. Minutes later, she randomly couldn't move her legs and collapsed. Now they were both in a panic. No one had considered the trajectory that she was shot at. Yeah, the bullet entered through her shoulder, but it had come to rest dangerously close to her spine. With every step, it was tweaked closer and closer and now, now she faced paralysis and possible death. The opportunity to escape the sewers with her life had left. Leonard would have to do surgery in the most disgusting surgical theater known to man.


	6. Surgery In a Hellhole

**Summary for the Chapter:**

> Leonard is forced to perform surgery on Katherine in the sewer. What could possibly go wrong? He has to come to terms with the possibility of her dying all over again, but this time it will be very real.

Leonard had helped many people in bad situations; it was part of his job. Calming down the wounded was never easy, they were scared and in pain; but it was never more difficult than sitting next to someone he loves, knowing deep down, they probably wouldn't make it out of there. He couldn't even fake confidence in the situation. It was all across his face like a story. Katherine knew that there was a really good chance that he was more afraid of losing her than she was of dying. She wasn't in a great deal of pain and if it wasn't for her inability to move her legs, she would have thought everything was okay. 

He just sat there begging her not to fall asleep. There wasn't much he could do until Jim and the group got back with medical supplies. He felt helpless, holding on to her hand. She was getting cold, her heart rate had started to decrease. Her breathing had gotten thin and she was slightly cyanotic. She was in bad shape, and he blamed himself. All of this could be traced back to him. He had gotten the crew captured, he had recognized her voice and convinced her to come out of her hiding spot, he had caused her to fail her mission and now she had gotten shot for him.

He wished he could say this was the first time that she had been shot for him, but it wasn't. His first mission as her partner had resulted in her getting shot in the leg. She had jumped in front of him, taking the bullet in the process, it was like out of an action movie, only real, painful, and bloody. She had been off duty for a month because of that. There was something about her and taking bullets meant for him, he didn't understand. He would gladly have taken them both for her.

At some point during his daydream, she had slipped into a deep sleep. He couldn't stop himself, he started crying. He knew that if he fell asleep her chances of waking up lowered and she had done just that. 

Jim had taken a group with him in search of the medical wing. Leonard had drawn a rough map from memory and it had been pretty accurate, even two hundred years in the future. He had given them a list of things to find:

  * Scalpel
  * Rubbing alcohol
  * gloves
  * forceps
  * gauze
  * suture kit



Spock had found most of the things while Jim looked around the room. This was the room where so many of John's friends had died or been hurt, but there wasn't any evidence that anything had ever happened here; not that he expected it to look destroyed still. 

By the time they made it back to the sewer, Katherine had lost consciousness and Leonard was crying. He couldn't shake the feeling of death lingering just behind him, watching Katherine, waiting for her. His anxiety was through the roof, he was about to attempt the impossible. He rolled her over and cleaned around the thin little line, the only evidence that she had been shot in the first place. He did his best to set up a makeshift sterile field. He didn't have much luck. 

Mustering up every ounce of nerve, he made the first incision. He was amazed at how steady his hands were in spite of how shaky he felt. Jim stood beside him, prepping tools and passing things back and forth. He knew how wrecked Leonard was, he was just glad he could be there for his friend right then. Leonard had to move quickly, it would take long for the incision to try and heal and the longer he took the weaker Katherine got. Jim handed him the forceps to try and locate the bullet, but all he found was blood. The bullet had vanished. It had moved so much that now, finding it was proving impossible. Spok setup the Tricorder and held it so that Leonard could track the bullet while digging around. He finally found it, but she had lost a lot of blood in the process. When he pulled it out he dropped it in the bin that Jim had grabbed to carry the stuff in. Just as he was about to wipe the blood out of the way so he could start closing her up, there was a loud bang followed by stuff falling off from the ceiling. He had almost pulled off the impossible, but some of it landed on Katherine. He cleaned the wound as carefully as he could, desperate not to push the goo further into the wound, but it was hard to tell if he had gotten it all. 

He decided not to sew the wound up given the introduction to infection. He bandaged it the best he could and carefully rolled her over. He pulled her into his lap and clung to her, begging her to wake up. He knew it wasn't likely. He had just been digging around in her shoulder and she hadn't so much as flinched. It was more or less safe to carry her out, there were no stitches to worry about and the bullet was out. He picked her up and carried her bridal style through the tunnels. 

When he had imagined carrying her like this, it was after their wedding and it was into their shared home. Instead, he was carrying her nearly lifeless body; if it wasn't for the occasional breath and the light thud he could feel through her back, he would have thought that she was already dead.

They resurfaced inside of the UAC base. He quickly recognized it as the ARK room. They could take the ARK to Earth and beam back onto the Enterprise. But someone would have to stay behind and trigger the Ark and blow up the base. Leonard didn't want to leave you behind, but ARK travel was unpredictable at best and he knew you weren't going to survive the trip through. He would rather die on that damn base then live without you. Jim rejected the idea immediately. Bones just sat against a wall with Katherine in his lap again.


	7. Someone Must Stay

**Summary for the Chapter:**

> Katherine wakes up during the debate over who should stay and volunteers. Leonard refuses to let her stay behind to save the crew. A random redshirt saves the day.

They had been bickering for what felt like hours, even though they had only been sitting there for ten minutes. Leonard had gone quiet. He knew that if Katherine didn't go through the Ark, neither would he. While Jim was yelling about being the Captain and saving his crew, Katherine woke up. She was alert and the color was starting to return to her face.

"I'll stay behind. Leonard, you and I both know I am not surviving that hell ride through the ark. It takes a toll on healthy people and we don't even know if I can walk. I am very old, I have no one who will miss me besides you, you have a crew to help and the crew needs their captain, so Jim can't stay. I am the only logical choice to stay behind. I am dead weight and I'll only get you killed." Her hand cupped his cheek. She never got tired of looking into his eyes and trying to figure out what color they were. 

"Whatever happened to leave no man behind? I am not letting you die here too! This isn't up for debate, Kat!" Leonard was terrified. Tears ran down his cheeks. He had just gotten her back. Jim was perplexed. Spock did his signature eyebrow raise.

"Doctor, the Staff Sergeant is correct. She is the only logical person to stay behind."

"I don't care about logical, Spock." Leonard raised his voice, and Katherine flinched.

"I could stay behind." He was a young Ensign that Leonard hadn't bothered remembering.

"No. I will stay behind. John, stop arguing with me. I was always meant to die here." At that, Jim ordered the discussion to end. It didn't matter who stayed behind, it would be a great loss.

Spock and Scotty started programming the ARK and got the detonators all set up. Katherine was shown how to set them off. Leonard had gotten up and walked away. He couldn't do it again. The crew gathered around the ARK circle and Katherine started it up. John went through first to demonstrate how it was done, then the rest of the crew followed by Jim. The Redshirt from before came up beside Katherine and told her to give him the detonator.  When she refused, he ripped it from her hands and shoved her through the ARK; closing it in the process.

Katherine landed hard on the floor and Leonard rushed to her side. When Jim asked what happened, she told him about the Ensign and his actions. When a connection was attempted with Olduvai, it came up with a busy signal. Olduvai was finally gone. 

* * *

Leonard took Katherine to Starfleet medical where he was able to go in and do surgery to correct all the damage that had been done by him, the bullet, and the goo. She made a full recovery and went on to go through the Academy as a Security cadet. She graduated in a year since she already knew everything minus Starfleet codes. Jim requested that she be assigned to the Enterprise, which the admirals unanimously agreed to. 

They weren't partners this time around, but they did work closely with one another. Leonard proposed to Katherine again and shortly thereafter they were married by Jim aboard the Enterprise. Leonard and Katherine did their best to rid themselves of their Past Identities. Katherine McCoy was the best security officer in the fleet and Leonard McCoy was the best doctor. They were no longer Death and Reaper, despite the tattoos that had always kept them bound to each other.


End file.
